This invention relates to fire-retardant foamed polymers.
U.S. Pat. No. 3,075,944 teaches the use of bromodiphenylethers with metal oxide synergists for making fire-retardantpolystyrene and polyethylene.
U.S. Pat. No. 4,151,218 teaches the use of the same synergistic fire-retardant system for copolymers of styrene and maleic anhydride alone and rubber-modified.
The use of volatile hydrocarbon blowing agents to prepare foams of polystyrene is well known. These blowing agents are flammable hydrocarbons such as pentane and hexane.
U.S. Pat. No. 2,911,382 teaches the use of mixtures of volatile hydrocarbon blowing agents and water or hydrated salts.
Canadian Pat. No. 844,652 teaches the use of water or hydrated salts as the sole blowing agent for copolymers of styrene and acrylic acid.